Previously known is a wrapping machine for winding a web of wrapping film from a roll around an object to be packaged. The wrapping film consists of a thin plastic film. The wrapping machine is provided with a film dispenser. The film dispenser comprises a frame provided with at least one guide element for guiding the film, which guide element is in contact with a first side of the film. Further, the film dispenser comprises an openable gate section which is provided with at least one guiding device which is in contact with a second side of the film opposite to the first side. The gate section is pivoted on the frame so that it can be moved between an open position and a closed position. Moreover, the film dispenser comprises a pre-stretching device for preliminary stretching of the film. The pre-stretching device comprises two pre-stretching rollers, a first pre-stretching roller which can be run operated at a first circumferential velocity and a second pre-stretching roller which is disposed at a distance from the first pre-stretching roller and can be operated at a second circumferential velocity differing from the first circumferential velocity. The pre-stretching of the film occurs as a result of the two different circumferential speeds of the pre-stretching rollers which are brought into frictional contact with the film portion between the pre-stretching rollers.
In the known apparatus, both pre-stretching rollers are attached to the frame of the film dispenser. Connected to the gate part are guide elements, such as backup rollers, which, in the closed position of the gate, are pressed against the pre-stretching rollers while the film is passing between them along a W-shaped path so that each pre-stretching roller is in contact with the first side of the film on the same side of it and the backup rollers in the gate are in contact with the second side of the film.
A problem with this prior-art apparatus is that it has a complex structure containing many different parts, such as guiding means, rollers, power transmission elements and the like, so the structure is expensive. The film is narrowed too much by the pre-stretching system as the distance between the pre-stretching rollers is relatively long. As the film narrows too much, the film area covering the object being wrapped becomes smaller.